The following entries are displayed when issuing the Linux w command: USER (login name), TTY (terminal name), FROM (the remote host), [email protected] (login time), IDLE (idle time), JCPU, PCPU, and WHAT (the command line of their current process).

The JCPU is the time used by all processes attached to the tty. It does not include past background jobs, but does include currently running background jobs.

The PCPU is the time used by the current process, named in the "WHAT" field.

The result of 'w -l' command is the exactly the same as the w command without any option. The 'w -l' is used if no option supplied with the Linux w command. That's why there is no '-l' option in the w command manual page.

The command 'w -s' result shows only USER, TTY, FROM, IDLE and WHAT entries.

Here is the Linux w command example with '-u' option supplied running in Ubuntu desktop command terminal. The command 'w -u' suppose to not print the USER entry if we switch user to root and run the command but it does not happens. See example below: